1. Field of the Invention
The present invention relates to washing machines, and more particularly, to a washing machine control method in which a water level reduction rate is calculated to determine an optimum water re-supply amount.
2. Discussion of the Related Art
Generally speaking, to perform washing using a washing machine in which laundry has been placed, a wash course is selected to determine a wash pattern, water is supplied to the washing machine according a predetermined water level based on the amount of laundry in the washing machine, and washing is performed based on the predetermined water level. After the water reaches the predetermined level, however, the laundry absorbs a portion of the water, which soon lowers the water level. In addition, if the selected wash course calls for heating the water to a predetermined temperature before performing a washing step, the heating cycle evaporates a portion of the water, which also lowers the water level. Accordingly, as the washing step proceeds, there is a gradual reduction in the water level, and the rate of water level reduction depends on the type and amount of laundry and the selected wash course.
To compensate for the water level being lowered as above, a washing machine control method according to a related art introduces an additional supply of water before proceeding with the washing step, so that the predetermined water level is maintained. Such a method is illustrated in FIG. 1.
Referring to FIG. 1, the method of the related art includes steps of setting a water level based on an amount of laundry (S101), supplying water according to a predetermined water level (S102), performing washing according to a selected wash course (S103), determining whether the water level has fallen to a substantially lower level that necessitates the supply of additional water (S104), and stopping the washing step while re-supplying a predetermined amount of water based on the set water level (S105). To determine whether to re-supply an amount of water, the water is continuously monitored using a water level sensor, which senses a water pressure of the water in the washing machine.
In the above method, however, the rate of water level reduction will determine the number of times of re-supplying the predetermined amount of the water. That is, if the amount and type of laundry absorbs a great deal of water or absorbs the water slowly, or if the heating cycle results in a significant amount of evaporation, there will be an increased repetition of the steps to complete the water supply. Since the washing step is repeatedly interrupted, the time to perform the washing is excessive. Moreover, the various washing machine components for performing washing and water supplying are stressed by being repeatedly stopped and restarted, which reduces the life of the washing machine.